SHARE-BASED COMPENSATION - Share-based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 9	$ 11	$ 13	$ 20
Service-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	7	6	11	9
Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	1	2	(1)	3
ILG Acquisition Converted RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	0	2	1	6
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	8	10	11	18
SARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	1	1	2	2
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 0	$ 0	$ 0	$ 0